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EVGA 780i GTLREF lanes?

post #1 of 4
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I just recently upgraded to the 780i from the 680i, and I noticed there was an option for mv in the GTLREF lanes. I've fairly new to overclocking and I can't seem to really find any discussion as to what these should be set to. I found a video but the guy was explaining if you had a quad core (his were set to 85mv) but I'm not sure if this applies to a c2d. Any info would be appreciated, thank you.
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vroom vroom
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post #2 of 4
I leave it on auto ATM. It is the specific voltage strenght that allows for OCing the quad cores. The 780i bios actually allows for GTL ref voltage to each of the 4 cores.

Here is the science on it

AnAndTech explain GTL in depth as it relates to Quad Core OCing in their DFI P35 review. Starting from here, you can read more on GTL.
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post #3 of 4
I have an EVGA 780i and I found this approach to work well for me.

1) Adjust your vtt to a low enough voltage so that prime 95 will fail after one or two iterations. ( I had mine around 1.5 volts @4.2 GHz.)

2) A good starting point for me was .30 on all four lanes.

3) boot up and start prime 95 on all for cores. and see which cores fail first.

4) Gradually raise or lower the voltage for the particular core that is failing first. (this can be a time consuming thing because it really is trial and error.) I found that core 2 would fail first and than core 1. core 0 and 3 were pretty stable until I got too high on the gtlref voltages. The funny thing was that it seemed core 1 needed more voltage than the rest and core 2 needed less. After some time I got all 4 cores to go about 3 iterations before failing. ( I ended up at .40, .50, .25, .40.)

5) now go in and raise your vtt up around .25 volts higher. (1.525 in my case) my system is now much!!! more stable than it was when I had them all on auto.
I hope this is helpful for someone because I know I was at a loss with a system that was un-stable for some time until I figured this out. GOOD LUCK!
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post #4 of 4
Sorry, GTLREF is NOT Vcore adjustment for the cores. It has nothing to do with Vcore. GTLREF is a reference voltage to set the signal filter level for inter-core communication, and adjustments are per die, not core. 1.2 VTT is enough for 400-420 mhz fsb with correct GTLREF adjustments, 1.3 up to ~450. Un-needed VTT increase will only introduce more unwanted heat and signal noise.

All you need to know about GTLREF and 780i mobo:

http://www.evga.com/forums/m.asp?m=476249
Edited by r0b0t c0rpse - 7/29/08 at 7:50am
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